1. Field of the Invention
The subject invention relates to a semiconductor device usable as an optoelectronic switch, pulse generator or optical detector.
2. Background of the Invention
Prior art optoelectronic switches are known which are based upon structures employing silicon or III-V semiconductor substrates. See Auston, U.S. Pat. No. 3,917,943 and Leonberger et al., U.S. Pat. No. 4,376,285. Such devices present several drawbacks including relatively slow turn-off speeds and reduced efficiency due to uncontrolled surface effects. For example, Auston requires a separate laser pulse to turn off his device as a result of the long minority carrier recombination time. Leonberger et al. propose a faster time without a laser turn-off pulse by using an indium-phosphide substrate. Such a device is still limited by the minority carrier recombination problem and therefore is relatively slow in turning off.
In Applied Physics Letters, 40, p. 255 (1982), Thanivavarn and Gustafson describe a fast optical detector fabricated of metal/tunnel oxide/silicon/tunnel oxide/metal. The tunneling oxide structure would appear to limit performance of the device and preclude it from operating in a steady high frequency mode.
It is an object of the subject invention to provide a device usable as a high frequency optoelectronic switch which avoids the long relaxation times and surface effects of prior art devices.
It is another object of the invention to provide such a switch employing an established fabrication technology.
It is yet another object of the invention to provide an optically activated, semiconductor microwave device having general application in microwave science, engineering and communication systems.